Duplex bag and process of making same



Oct. 2, 1951 H. F. WATERS 2,569,964

DUPLEX BAG AND PROCESS OF MAKING SAME Original Filed May 14, 1940 NON- FUS/ELE GOA TING IN V EN TOR.

Patented Oct. 2, 1951 DUPLEX BAG AND PROCESS OF MAKING SAME Harry F. Waters,,New York, N. Y.

Application July 10, 1944, Serial No. 544,185, which is a division of application Serial No. 335,045, May 14, 1940. Divided and this application December 4, 1947, Serial No. 789,747

4 Claims. 1

The present invention relates to improvements in the bag making art and, more particularly, to an improved form of bag of the duplex type having automatically opening bottoms, and to a method of roducing the same.

This application is a division of my application erial No. 544,185, filed July 10, 1944, now Patent No. 2,444,762 of July 6, 1948, which is a division of application Serial No. 335,045, filed May 14, 1940, now Patent No. 2,353,605, of July 11, 1944.

As those skilled in the art of paper bag making know, bags used for packaged products, particularly food products, were to a substantial extent, of the types known as automatic opening satchel or diamond-fold bottom bags. The manipulation of kraft or other paper bag material into these types of bags make it extremely difficult, if not impossible, to produce a bottom which is siftproof. In the past various attempts were made to make the bottom of these types of bags siftproof, either by using a supplemental patch member or by providing additional folds in the bottom to obtain the same result. These attempts were not satisfactory due to the fact that they were expensive and in the latter instance resulted in though from time to time various other suggestions and proposals were made to solve the outstanding problem, none, as far as I am aware, of these prior suggestions and proposals was completely satisfactory and successful on a practical and commercial scale.

It is an object of the present invention to eliminate the foregoing difficulties and disadvantages experienced in the manufacture and use of bags of the automatically opening bottom type.

It is another object of the present invention to provide a bag having a bottom of the automatically opening type in which complementary lines of adhesive are provided along pre-determined lines of the material of the bag which is subsequently going to form the bottom in such a manner that these lines of adhesive are brought into cooperating relation and form a continuous dam or wall interposed between the folds of the bottom and the exterior of the bag.

It is a further object of the present invention to provide a sift-proof and substantially fluidtight bag having lines of a suitable adhesive provided in predetermined regions thereofisaid adhesive being adapted to be fused after the formation of the bottom structure to convert the bag into a sift-proof and in some cases substantially fluid-tight structure.

The invention also contemplates the provision of predetermined regions on the fusible surface of a bag having a non-fusible layer or coating thereon which in the formed-up condition of the bag prevents such regions from fusing and adhering to each other upon the application of heat and pressure thereto.

It is also within the contemplation of the present invention to provide a novel and improved method for the quantity production of sift-proof bags of the automatic opening bottom type which is simple in character and which may be carried out with great facility on a practical and industrial scale by means of existing machinery without requiring any complicated and expensive changes.

Other and further objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings in which:

Fig. 1 illustrates a plan view of a pair of webs employed in the manufacture of a bag of the duplex type;

Fig. 2 depicts a fragmentary perspective view of the end portions of the superposed strips of sheet material employed in making the duplex bag of the invention;

Fig. 3 shows the bottom structure of the duplex bag in one of the preliminary stages of its manufacture;

Fig. 4 is a similar view .of the bottom structure of the bag as shown in Fig. 3 prior to its completion; and

Fig. 5 is a perspective view of a finished bag embodying the invention with its bottom portion turned up.

Broadly stated, according to the principles of the invention I obtain the desired sift-proof quality of the bottom by providing asuitable adhesive, preferably of the reactivable or fusible type, along predetermined lines on the material of the bag which is to form the bottom. This adhesive is provided in such regions and in such a manner that as soon as the web or strip is converted into a tube with a preformed bottom, these regions of adhesive will be brought into a contacting or cooperating relationship and a continuous dam or wall will be interposed be tween the folds of the bottom and the exterior of the bag. This desirable result may be accomplished in various ways. Thus, when for simplicity of manufacture it is preferred to provide all of the adhesive regions on one side of the Web, the web may be provided with longitudinal strips of adhesive adjacent to the side edges thereof. These longitudinal lines of adhesive are supplemented by a continuous line or strip of adhesive'extending across the web in such a manner that upon the formation of the bottom structure these lines of adhesive will be brought into complementary or cooperative relation and into a single plane. After the bottom has been formed, these cooperating lines of adhesive may be fused by the application of a heated pressure surface against the exterior of the bottom structure whereby a continuous dam of fused adhesive will be interposed between the interior and the exterior of the bag. As a modification of this concept, a web of non-fusible sheet material may be provided with reactivable adhesive in predetermined regions on both sides thereof, said regions being automatically brouught into registering and cooperating position during the formation of the bottom structure.

It is also possible to apply the principles of the invention to bags of the so-called duplex type, in which generally a non-fusible external sheet or web and a fusible internal liner web are arranged in superposed position. In these types of bags the complete inner surface of the big is fusible and in order to obtain the desired selective adhesion, it is necessary to render predetermined regions thereof non-fusible. This may be accomplished in various ways such as by applying a layer, or coating, of non-fusible material to such regions. This non-fusible layer may be connstituted by a patch of paper, or of a coating material which is either non-fusible or, in case it is fusible, has a higher melting point than of the fusible liner material. In such a case, whenthe bottom structure is formed, and

a heated pressure surface is applied thereto, only those regions will be fused together where a dam or fusion seam is desired while the other regions of V the inner surface ofthe bag remain unaffected. It will be noted that in all of these various forms of my invention the essential concept is to provide an automatically opening bottom in a bag which is originally not sift-proof and to finally convert this imperfect bottom structure into a completely sealed and sift-proof bottom structure by the application of heat and pressure to predetermined regions of the finished bottom surface.

In my parent application, above identified, the two embodiments of the invention are concerned with bags constituted of a non-fusible material such as paper and provide bags which although positively sift-proof are not completely fluidtight. According to the present invention it is possible to incorporate the principles of the invention into bags which are of a positively fiuidtight character and which may be employed for packaging liquids or other materials in a hermetically sealed condition. This is accomplished by providing a fluid-tight inner surface for the bag, either by coating the material thereof with flexible, fluid-tight and fusible material, or by securing an internal fusible lining of fluid-tight character to an external non-fusible sheet. Figs. 1 to 5 illustrate a practical embodiment of the invention in a duplex bag having an' external non-fusible layer and an internal liner of a fluidtight and fusible character, such as, for example, a rubber hydrochloride product known under the trade name of Pliofilm. Referring now to Figs.

1 and 2, a web structure of duplex character is shown comprising an external web 62 constituted of non-fusible sheet material and an internal web 63 connected thereto in an offset relation and constituted of a fusible and fluid-tight material. These two webs are folded along a plurality of longitudinal lines 64, 65, 66, 61, 68 and 69 and the lateral edges of both the external and of the internal web are selectively secured together to provide a tube having main panels H3 and El and end panels l2 and 13. Generally speaking, it is preferred to employ an ordinary adhesive for securing the edges of the external web together and to employ fusion by heat and pressure to secure the edges of the internal web together. Conventional cuts 14 and 15 are made in main panels 10 and H either as a preliminary step in making the ba or after the tube is formed and provide tabs 16 and H. The relative arrangement of webs t2 and 63 best observed in Fig. 2 which also clearly shows that web 62 is provided with a cut-out marginal portion 18, extending transversely along part of main panel 1B, end panel 12, and a portion of main panel H. Inner fusible liner 63 is also provided with non-fusible regions 19 and in the central portions of main panels H3 and H subsequently formed therefrom. The object of non-fusible regions 19, 80 and of cut-out portion 18 will be further explained as the description proceeds.

omitting the various intermediate stages of the procedure followed in converting webs 62 and 63 into a tube and in forming a flattened rectangular bottom structure, which is closely similar to the one followed in the previous embodiments of the invention, as described in my parent application, the structure illustrated in Fig. 4 is obtained.

This figure shows the bottom already formed and closed but tabs 16 and 1'! extending in opposite directions. The cooperation of the various layers in this position will be best seen inFig. 3, showing the terminal portions of thebottom structure bent up to make the arrangement of the inner liner readily discernible. It will be noted in Fig. 3 that in this condition of the bottom struc ture the terminal edges of-the inner liner will be brought into an overlapping position and provide a closure for the interior of the bag. On the other hand, the terminal and overlapping portions of the inner liner are not completely covered but are exposed to the exterior due to the presence of cutout portion 18. When the bottom structure so formed is now folded together along fold lines 8| and 82, tabs 16 and 11 are folded one above the other and are adhesively secured and complete the bottom structure of the bag. However, it is obvious that the folds of the bottom structure would be far from being sift-proof or fluid-tight and the value of the bag would be hardly superior to that of a conventional bag. A simple heat-sealing operation will convert this structure into one of a complete sift-proof and fluid-tight character.

This operation consists in the application of a heated pressure surface against a narrow strip of the bottom'structure indicated by reference character 83 in Fig. 4. This heated pressure surface will fuse the coperating portions of the inner liner into a fluid-tight structure having seams fluid-tightly bonding the overlapping edges of the liner and als fusing the resulting tabs 84, 85 of the liner to said seam due to the presence of cut-out portion 18 which permits direct contact of the intermediate portion of seam 86 with its terminal portions. In this final operation it will be noted that the provision of non-fusible regions 19 and 80 in main panels H and ill prevents fusion of the inner surfaceof the liner tube together pressure surface against the regions to be heatsealed the inner wallsof the liner would be fused together in the same region and would render the bag practically useless. Non-fusible regions and 80 on the fusible liner may be provided in various ways, such as, for example, by adhesively securing a patch member of paper, and the like, thereto or by coating or printing such regions with a suitable material which is either non-fucible, or, if fusible, has a melting point which is higher than that of the liner. Examples of such materials are nitrocellulose and cellulose acetate, although, of course, a great variety of equivalent materials are known to those skilled in the art.

The finished bottom structure of the bag is seen in Fig. 5, showing a perspective view of the finished bag with its bottom turned up. It will be observed that the bottom structure has a conventional appearance but, of course, provides characteristics of sift-proofness and fluid-tightnes's which were impossible to obtain prior to the present invention.

The materials employed in the bags embodying the invention may be of various character according to the packaging problem contemplated. The non-fusible web is generally constituted of paper although other materials of a non-fusible character, such as metal foils, may be employed with equal or similar results. The fusible adhesive may be constituted of a suitable rubbery material, such as rubber hydrochloride compound sold under the name Pliofilm, and various synthetic resins of which a vinyl resin sold under the name of Vinylite is an example. These fusible adhesives are preferably applied to the surface of the non-fusible web by means of a printing, coating or spreading process in the form of a solution in a volatile solvent. The preferred material for the fusible liner of the duplex bag embodying the invention is Pliofilm.

It will be noted that the present invention provides various novel types of bags of the automatically opening bottom type having a complete- 1y sift-proof and in many cases even fluid-tight character. Of course, these important new resuits and advantages could not be obtained by means of conventional bags of the automatically opening bottom type all of which are subject to leakage to a lesser or greater extent.

Other important advantages of the present invention reside in the circumstance that as far as actual mechanical manipulations of the sheetlike material are concerned, these are similar to the manipulations followed in making conventional bags of the automatically opening bottom type so that existing machinery may be used with slight changes. The critically important difference resides in the provision of my adhesive lines or non-fusible regions of special arrangement which are subsequently brought into complementary and cooperating position and which may be subsequently fused together into a siftproof or fluid-tight structure by the simple ex pedient of applying a hot pressure surface thereto.

Therefore, my novel bags may be readily manue factured on a quantity production scale with existing machinery which only has to be supplemented with a heat sealing device of appropriate character.

Although the present invention has been described in connection with a few preferred em bodiments thereof, variations and modifications may be resorted to by those skilled in the art without departing from theprinciples of the present invention. Thus, although I have shown'principally bags having reentrant end walls, which are generally referred to in the art as ABC bags, obviously, the same inventive concept may be employed for bags of the type in which the end walls are folded outwardly along their medial lines and which are referred to in the trade as satchel type or diamond fold type bags. I' consider all of these variations and modifications as within the true spirit and scope of the present invention as described in the foregoing description and defined by the appended claims.

What I claim is:

l. A duplex bag of the automatically opening bottom type which comprises in combination an outer tube of non-fusible sheet material, an inner tube of fusible sheet material within said nonfusible tube and forming a liner therefor, said tubes being folded longitudinally along a plurality of lines to forma pair of end panels and a pair of main panels connected to saidend panels, a preformed rectangular bottom structure flattened in the plane of said main panels including the lower marginal edges of said outer and inner end panels folded towards each other at least the edges of said inner fusible end panels being in an overlapping position and the resulting tabs being folded above each other, a deposit of a non-fusible material on the inner surface of said inner tube in the region of contact of the overlapping edges of said end panels and of th inner surface of said fusible tube, and a heat-fused seam substantially hermetically sealing said overlapping fusible end'panels and said bottom structure whereby said non-fusible deposit will prevent fusion of said seam to the inner surface of said inner tube.

2. A duplex bag of the automatically opening bottom type which comprises in combination an outer tube of non-fusible sheet material, an inner tube of fusible sheet material within said nonfusible tube and forming a liner therefor, said tubes being folded longitudinally along a plurality of lines to form a pair of duplex reentrant end panels and a pair of duplex main panels, a preformed rectangular bottom structure flattened in the plane of said main panels constituted of the lower edges of said outer and inner end panels folded towards each other and the resulting tabs being folded above each other, the lower edges of said inner tube being in an overlapping position in which they may be fused together to form a substantially hermetically closing seam for the bottom of said bag, a deposit of a non-fusible material on the inner surface of said inner tube in the region of its contact with said bottom seam to prevent fusion of said seam with the inner surface of said inner tube, and a cut-out portion in the lower marginal portions of said nonfusible end panels to permit direct contact and fusion of the tabs of said inner tube with said seam.

3. The process of making a duplex bag of the automatically opening bottom type which com-- 7 panels and a pair of side panels, applying a line of non-fusible coating to the inner surface of the main panels of the inner tube in predetermined regions thereof, folding the terminal regions of said main and end panels together to form a rectangular bottom structure in which the bottom ends of the inner tube are brought together into an overlapping position, and applying a heated pressure surface against the exterior of said bottom structure whereby said overlapping bottom edges of said inner tube are fused together and form a fluid-tight seam and heat fusion of the inner walls of said inner tube in the regions underlying said seams is prevented by said non-fusible coating.

4. The process of making a duplex bag of the automatically opening bottom type which comprises providing a web of non-fusible sheet material and a web of fusible sheet material in a laterally staggered arrangement, folding said webs along a plurality of longitudinal lines and selectively securing the lateral edges thereof together by adhesion and heat-fusion respectively to form a non-fusible outer tube and a fusible inner tube both having a pair of main panels and a pair of end panels, applying a line of a nonfusible coating to the inner surface of each of the main panels of the inner tube in predetermined regions thereof, making a pair of incisions in each of the main panels of said non-fusible web to provide a pair of tabs, cutting out a transverse strip in said non-fusible web between said tabs,

folding the terminal regions of said main and end panels together to form a rectangular bottom structure in which the bottom ends of the inner tube are brought together into an overlapping position in the region of the cut-out portion of said non-fusible web and the resulting tabs of the inner tube are in direct contact with said overlapping portions thereof, and applying heat and pressure against a strip of the exterior of said bottom structure in the region of said overlapping portions whereby said overlapping bottom edges of said inner tube are fused together and form a fluid-tight seam and heat fusion of the inner walls of said tube in the regions underlying said seam is prevented by said nonfusible coating. 7

HARRY F. WATERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,973,391 Reynolds et a1 Sept. 11, 1934 2,133,946 Bloomer Oct. 25, 1938 2,151,202 Guyer Mar. 21, 1939 2,152,323 Moore Mar. 28, 1939 2,246,911 Baker June 24, 1941 2,347,439 Shea et al. Apr. 25, 1944 2,353,746 Moore July 18, 1944 

